Technical Field
This application relates to an optimization method and device for a brightness compensation data volume, in particular, an optimization method and device for a brightness compensation data volume implemented by using information stored in an external memory.
Related Art
Planar displays have numerous advantages such as a thin body, power-saving, and no radiation, and are widely used. Existing planar displays mainly include Liquid Crystal Display (LCDs) and Organic Light Emitting Displays (OLEDs). Because of having advantageous characteristics, such as self-illumination without using a backlight source, high contrast, small thickens, high response speeds, applicability to flexible curve panels, broad service temperature ranges, and relatively simple structures and processes, the OLEDs are considered to be novel application technologies of next-generation planar displays. However, because in an OLED display, OLED components may be different in terms of luminance because of losses in a process or use, a non-uniform brightness phenomenon (Mura effect) is likely to occur.
Currently, because of reasons such as a production process, a to-be-compensated area with non-uniform brightness (Mura) may often occur in a production process of a planar display panel, and a bright spot or a dark spot occurs, resulting degradation of display quality of the panel. A brightness compensation (Demura) technology is a technology of removing display Mura, to make screen brightness uniform. A basic principle of the Demura technology is: making the panel display a gray level screen, photographing a to-be-compensated panel by using a brightness obtaining apparatus, for example, using a capacitive coupling component camera (Charge Coupled Device, CCD), obtaining a brightness value of each pixel unit in the to-be-compensated panel, and then, adjusting a gray level or a voltage of a pixel unit in an area of a to-be-compensated position (Mura), to brighten an excessively dark area or darken an excessively bright area, thereby achieving a uniform display effect.
However, currently, a Demura device generally requires a camera capable of accurately photographing a pixel unit. In this way, an advantage is that a most accurate value of a to-be-compensated position (Mura) can be obtained. However, high requirements are raised on a resolution and calculating and processing capabilities of a Demura camera, and there is no capability of compensating for relatively small Mura.
Further, when the Demura technology is applied to actual production, not only a good display effect is required, but also a short consumed time is required. Therefore, a good and practical Demura algorithm is needed. In a Demura algorithm used in the prior art, a gray level after correction is usually estimated according to a gamma value and target brightness. In an OLED display panel, gamma curves of respective pixels, particularly, in a Mura area, are greatly different from each other, and an expected compensation effect cannot be achieved by performing estimation once according to a uniform gamma value or gamma curve.
However, currently, this technology uses a central area of a to-be-compensated panel as a reference point, obtains a difference by comparing brightness of an other to-be-compensated position area with brightness of the central area, and further calculates, according to a standard gamma curve (Gamma 2.2 curve), brightness compensation data (including compensation brightness and a compensation gray level) needed to compensate, so as to make brightness of the entire panel uniform.
At present, this approach is relatively simple and easy. However, a premise of calculating the brightness compensation data is assuming that the to-be-compensated panel is already of a standard gamma 2.2 curve. However, in an actual production process of panels, it is impossible to perform accurate management and control on a gamma curve of each panel. In addition, a to-be-compensated position (Mura) at a central point usually cannot be removed. Consequently, a final effect of Demura is relatively likely to be affected.
Meanwhile, calculation is performed for each area by default, and in addition, to ensure a Demura effect, a smallest unit in an area of a to-be-compensated position cannot be excessively large (usually including 8*8 pixel units). Therefore, a volume of final brightness compensation data of the entire to-be-compensated panel is relatively large, and accordingly, an external memory (Demura flash) needs to have a relatively large capacity, an internal RAM of a processing IC on a driver board also needs to be relatively large, and further, limitations in a data transmission time and rate would be caused.